佛說觀佛三昧海經 4.16

4.16

"How does one contemplate the light of the Tathāgata's mouth? Its light is white, resembling a jeweled mountain, pure both within and without. Within the jeweled mountain are immeasurable transformation Buddhas of pure refined golden color. At that time, light emerges from the mouths of the transformation Buddhas; its light is of five colors, shining everywhere across the ten directions and entering the mouths of the Buddhas. When this mark appears, whether walking, standing, sitting, or lying down, the practitioner constantly hears the Tathāgata expound the four applications of mindfulness (body, feelings, mind, and dharmas), and expound their cognitive objects so that the practitioner hears them. Having heard them, they retain them in memory, close their eyes, and contemplate them; through the power of this light, they immediately attain the dharmas of the four applications of mindfulness. At that time, the Buddhas of the ten directions and Śākyamuni each extend their right hand during samādhi, stroke the practitioner's head, and say: 'Excellent, excellent, good man! You are truly able to practice the concentration of mindfulness of the Buddha.' Such contemplation is called right contemplation; if one contemplates otherwise, it is called wrong contemplation.